Ebanz stohb



July 3, 192s.

F. STUHR METHOD OF BAKING THE LININGS OF CRUCIBLES Filed June 29, 1927 I5 TI'ORNEY Patented July 3, 1928.

UNITED STATES 1,675,735 PATENT OFFICE.

FRANZ s'ronn, or ESSEN/RUEB, ennmy.

METHOD OF BAKING THE LININGS OF CBUCIIBLES.

Application filed June 29, 1927, SeriaINo. 202,292, and in Germany November 18, 1926.

The invention relates to the method of baking the linings of crucibles generally employedin alumino-thermic operations and provided with a bottom tap opening, said.

oible.

Orucibles usually employed for carrying out the alumino-thermic operation, more especially in forming welds and castings, consist of an iron shell lined with a suitable refractory material, such as magnesite in combination with a cohesive or binding agent, preferably tar, the magnesite mixture being applied to the interior of the shell in a plastic condition. Before these crucibles can be used, it is necessary that the lining be thoroughly baked in order to drive off all of the volatile elements thereof and leave the refractory magnesite alone to constitute the lining. -Heretofore these operations have been carried out in a special furnace in which the lined crucibles were surrounded by hot gases.

The present invention. is designed to obviate the expense of constructing and maintaining these heating furnaces and to admit of the crucibles being quickly and effectively lined or relined at the places where they are used, or at other convenient places. The application of the method is illustrated in the accompanying drawings, in which Fig. 1 is a side elevation, part1 in section, of a single crucible associated wit the means for effecting the baking of the lining thereof.

Fig. 2 is a sectional elevation of two crucibles arranged for the simultaneous baking of the linings thereof.

Referringto Fig. 1 of the drawings, b indicates the shell of a crucible, such as commonly employed in alumino-thermic'operations, provided with a tap hole'h in the bottom thereof, by means of which the products of the alumino-thermic reaction are discharged from the crucible. The crucibles are provided with a lining e of refractory material, primarily to protect the iron shell from the superheated products of the reac-' tion, which lining, as stated, preferably consists of magnesite admixed with tar and applied as a coating or lining, while in plastic these a baking the linings of crucibles is that the 1 operation may be carried out at a minimum condition, to the interior of the shell. After thelining has been applied, the crucible is preferably placed on its side and supported in position by a suitable block a. The open end of the crucible is closed by means of a suitable cover -c, preferably of iron or the like, provided with a central opening d, and a et of combustible fluid fuel from any suitable source, as, for example, a blow torch or a portable reservoir containing an. admixture of combustible gases producing a relatively hot flame,'as conventionally illustrated at f,

is directed through the opening, so that the burning gases come in contact with the plast1c lining and heat the same so as to drive off all of the volatile constituents in the linmg and bake the latter until it is entirely dry and efiectively resistant to the, products of the alumino-thermic-reaction.

Preferably, in order to maintain the lining I in proper position during this baking or drymg operation, the inner surface of the lining is covered with'a metallic sheath, which may take the form of a frustum vof a hollow cone 9 with the small open end thereof in alignment with the tap opening of the crucible, which sheath is removed after the baking operation has been completed. When two crucibles of substantially the same size are to be lined or relined, they are preferably positioned as shown in Fig. 2, namely,-with their open ends juxtaposed at the rims thereof, thereby mutually closing the tops of the crucibles, after which the jet of combustible "fluid fuel is introduced throughthe tap opening of one crucible, and the products of combustion exhausted thg'lough the tap opening of the other cruci e.

The particulalr advanta of either of ternative modes 0 applying and of labor and expense at the places where the crucibles .are used and with apparatus commonly employed in alumino-thermic o erations, as, for example, the ordinary b ow pipes or torches usually employed for preheating the interior of the molds and the sections of. the materials enclosed therein, which are to be Welded. What I claim is: 1. The method of baking the refractor linings of crucibles provided with an open top at oneend and a tap opening at the other end, which comprises applying a closure to top of the crucible, projecting a combustible tops of the cruci fluid jet through an opening in the closure, and venting the products of combustion through the tap opening.

3. The method of baking the linings of crucibles rovided with bottom tap openings, whic comgrises mutually closing the les by juxtaposing the top rims thereof, introducing a combustible fluid jet through the tap opening of one crucible and exhausting the products of combustion thgfugh the tap opening of the other cruc1 e.

4. The method of baking the linings of crucibles rovided with bottom tap openings, whic comprises covering the plastic limngs with metallic sheaths, mutually closing the tops of the crucibles by juxtaposing the top rims thereof, introducing a combustible fluid jet through the tap opening of one crucible and exhausting the products of combustion through the tap opening of the other crucible.

In testimony whereof I afiix my signature.

FRANZ STOHR. 

